One of Australia's leading demographers says the political debate over population is in danger of scapegoating migrants to cover up for a lack of adequate government planning.

Australian Demographic and Social Research Institute head Peter McDonald says he does not think Australia's immigration levels will drop off, because demand for workers is too strong.

And he says political leaders should stop talking about population predictions for 2050 and instead focus on the next 10 years.

Prime Minister Julia Gillard has focused heavily on the pressures facing big cities as Australia's population grows and has declared that she does not believe in a "big" Australia.

But the debate over size has become increasingly linked to the country's immigration numbers and the arrival of asylum seekers by boat.

As the outer suburbs of cities such as Melbourne and Brisbane struggle to deal with traffic and congestion problems, Professor McDonald has told Radio National that the debate is unfairly targeting migrants.

"I think there is a bit of a danger that we'll be scapegoating migrants for what is essentially the planning phase of government," he said.

Professor McDonald says migrants will be needed to fill jobs as the mining boom continues and baby boomers retire.

"That makes immigration inevitable as a way of meeting labour demand," he said.

"The issue then becomes better management of population growth. You can't run away from the issue of planning in our big cities. What we really need to be dealing with is the next decade."

He also says that most people coming into the country now are temporary workers, not permanent residents, and overseas students are also counted in population numbers.

When asked yesterday if the country's immigration intake had to be reduced as a way of controlling population numbers Ms Gillard replied: "I don't think this is a immigration debate."

"I think it's bringing into play issues about water, about soil, about city planning, about infrastructure and services, about getting skilled people where we need them."

The Opposition has seized on her comments today.

"If it's not about immigration, what is it about?", Coalition frontbencher Christopher Pyne told AM.

"Is she seriously suggesting that we are going to have a one-child policy in Australia to reduce the population, or is she planning on handing around condoms to make people reduce our population naturally?"

Sustainable Population Minister Tony Burke says the immigration issue is just one part of population policy.

"It's one of the issues that feeds into it, but let's not pretend that the major population pressures are being driven by those issues," he said.

"The major population pressures are being driven by people moving from one part of Australia to another."